As is well known, for the purpose of preventing intrusion of foreign matters such as dust into a joint and preventing leakage of a grease sealed inside the joint, a boot is mounted, for example, to a constant velocity universal joint incorporated into a power transmission mechanism of an automobile.
An example of the boot of this type is illustrated in FIG. 4. This boot 31 mainly includes a large diameter portion 32, a small diameter portion 33, a bellows portion 34, and a shoulder portion 35. Meanwhile, a constant velocity universal joint 36 mainly includes an outer joint member 37, an inner joint member (not shown), and a torque transmitting member (not shown) for transmitting torque being interposed between the outer joint member 37 and the inner joint member. The large diameter portion 32 of the boot 31 is engaged on the opening end side of the outer joint member 37 of the constant velocity universal joint 36, and tightened with use of a boot band 38 so as to be fixed. The small diameter portion 33 of the boot 31 is engaged with a shaft 39 coupled to the inner joint member of the constant velocity universal joint 36, and tightened with use of a boot band 40 so as to be fixed.
Incidentally, when the large diameter portion 32 of the boot 31 is engaged with the outer joint member 37 of the constant velocity universal joint 36, there is a risk in that the large diameter portion 32 moves past a predetermined position of the outer joint member 37 illustrated in FIG. 4, to which the large diameter portion 32 is fixed. To deal with this problem, in the invention according to an embodiment of Patent Document 1, over the shoulder portion and the bellows portion of the boot, the upright portion is formed which forms an angle of 85 to 90 degrees with respect to an axial direction, or desirably, an angle of about 90 degrees. With this structure, when the large diameter ring portion is engaged with the housing portion, the upright portion is engaged with the housing portion, whereby the large diameter ring portion is engaged with the housing portion at a predetermined position.
[Patent Document 1] JP 09-96318 A